Influences of sodium salt erosion on the self-healing ability and fatigue life of bitumen

Abstract

In this paper, the method of vibration immersion erosion was designed to simulate the sodium salt erosion of bitumen, and the modified dynamic shear rheology (DSR) tests were applied to explore the self-healing ability and fatigue life of bitumen in different sodium salt erosion environments. Moreover, the main reasons for the bitumen performance change were explained from the microscopic level by the four-component test, Fourier-transform infra-red (FT-IR) spectroscopy, and scanning electron microscopy (SEM). The significance ranking of different influencing factors (salt solution concentration, erosion time, and temperature) was determined by the F-test, and the correlation between the self-healing ability and fatigue life of the bitumen in salt erosion environments was analyzed. It was found that the self-healing ability and fatigue life of the bitumen were severely weakened in sodium salt solutions. Na2SO4 had the most prominent weakening effect, followed by CH3COONa and NaCl. The microscopic analysis revealed that the colloidal balance of the bitumen was destroyed under sodium salt erosion and the interaction between sodium salts and some radical groups of the bitumen resulted in the deterioration of bitumen fluidity, stability, and mechanical properties, resulting in the decline of the self-healing ability and fatigue life of the bitumen. The rankings of different influencing factors on the self-healing ability and fatigue life of the bitumen were temperature > concentration > time and temperature > time > concentration, respectively. The correlation analysis expressed that the negative impacts of sodium salts on the self-healing ability and fatigue life of the bitumen were highly synchronized.